Checking components
Signal missing. Permanent or intermittent fault.
Using VIDA vehicle communication, check the function of the brake light switch by reading off the parameters "Brake light switch" and "Brake pedal position". When the brake pedal is depressed, the parameter "Brake light switch" should indicate that the switch is activated when the parameter "Brake pedal position" is greater than 23.8% (1.2 V).
Diagnostic trouble code ECM-9400 will be stored in the engine control module (ECM) if the brake light switch has not closed when the brake pedal is depressed and brake pedal position is less than 23.8% (1.2 V) for longer than 0.16 seconds.
If the brake light switch and brake pedal position sensor appear to be working properly, but the brake light switch closes at the wrong time, check the attachment of the brake light switch and the brake pedal position sensor and check that the pedal assembly seems OK.
If the brake light switch does not close when the brake pedal is depressed, check the brake light switch's cables, connectors and voltage supply (battery voltage) to brake light switch terminal #1.
When the brake pedal is depressed (switch closed), brake light switch terminal #2 and engine control module (ECM) terminal #B26 should have battery voltage.
Remedy as necessary.
If diagnostic trouble code ECM-9400, No signal, Intermittent fault, is stored but no fault is found, the solution could be to download the upgraded software (only for markets where upgraded software (released 2006 or later) is available). Since detection time has been increased from 0.16 to 2 seconds and the fault must be repeated during 30 consecutive brakings, the upgraded software will be much more tolerant to short, intermittent disruptions.
The upgraded software has adjusted limits for the fault type No signal. The diagnostic trouble code is stored if the brake light switch is not closed when the brake pedal is depressed, brake pedal position is less than 53.9% (2.7 V) for longer than 2 seconds and this is repeated for 30 consecutive brakings.
The diagnostic trouble code can also be stored if the brake light switch is closed when the brake pedal is released. For this test an adapted brake pedal position sensor value is used, that is, the control module adapts the signal so that it always shows 0 % (0 V) at released pedal, which is different from other tests where the direct signal from the sensor is used. This parameter is not accessible in VIDA. By checking what the parameter "Brake pedal position" indicates when the pedal is released and then subtracting the value from the value indicated when the brake light switch is closed, one can estimate the size of the adapted value.
For example, if "Brake pedal position, volts" is 3.10 V when the pedal is released and 2.91 V when the brake light switch closes, the adapted value is 0.19 V (3.10-2.91) when the brake light switch closes. The diagnostic trouble code will be stored if the brake light switch is closed when the adapted value is less than 2.7% (0.14 V) for longer than 2 seconds and this is repeated for 30 consecutive brakings.
HINT: Using VIDA vehicle communication, check that the parameters "Brake pedal position, volts" and "Brake light switch" indicate correct values. To aid fault tracing, use Component specifications when measuring and checking relevant components and use Wiring diagram, Signal description and Breakout box to measure and control signals to and front the control module or its components.
Remedy as necessary
Other information:
- To connect the breakout box / access the control module, see Connecting the breakout box
- For information about signals, see ELECTRICAL SYSTEM
- For the resistance values, see below.
- See Identifying upgraded software ECM/ETM
- See Checking wiring and terminals
Caution: In order for Electronic throttle module (ETM) to reset any reconfigurations as well as delete internally stored problems, the following must be performed:
- Ignition off, wait three minutes so that the main relay / system relay releases the voltage feed to, among other, Electronic throttle module (ETM).
- Then turn on the ignition and turn it off again.
- Wait another three minutes, but if the electric cooling fan is running you have to wait another two minutes after the cooling fan has stopped, to ensure that Electronic throttle module (ETM) is shut off correctly.
If this is not done correctly, diagnostic trouble codes may remain even after deleting diagnostic trouble codes and any reconfiguration may remain, despite the problem being fixed.
Continue.
- Continue
Refer to Information